Origin of ferroelectricity in SbSI

Abstract

Abstract There are three phases in the phase diagram of SbSI: ferroelectric (T < 298 K), antiferroelectric (298 < T < 410 K) and paraelectric (T > 410 K). In the antiferroelectric phase the arrangement of the polar chains becomes antiparallel (up and down). It causes a disorder of the Sb atoms. Ferroelectricity and phase transitions in SbSI are closely related to its electronic structure and phonon interaction. The disorder results in an asymmetric double-well soft-mode potential. It leads to threefold splitting of the soft mode frequency. They all show large absorption peak and deep dielectric dispersion in millimeter and far IR region.